1. Field of the Invention
This invention relates to capacitors for electrical and electronic circuits, and more particularly to an improved metallic capacitor having a high capacitance and low physical volume. This invention also relates to the method of making the improved metallic capacitor through a wire drawing process.
2. Information Disclosure Statement
Over the years, the size of electronic components has decreased steadily and dramatically in the electrical and electronic art. Along with such dramatic decrease in the size of electrical components, the speed and complexity of electronic components has increased substantially in the electrical and electronic art. The decrease in size of electronic components has been primarily within the areas of semiconductors and resistant elements. However, such dramatic decreases in size have not been effected in the area of electrical capacitors.
A capacitor is formed by two conductive plates separated by a dielectric interposed between the two conductive plates. The capacitance of a capacitor is directly proportional to the area of the conductive plates of the capacitor and is inversely proportional to the separation of the conductive plates or the thickness of the dielectric. The dielectric of a capacitor must be of sufficient thickness to withstand the voltage potential between the conductive capacitor plates while being sufficiently thin to increase the capacitance of the capacitor.
It should be understood that any reduction in size of a capacitor is limited by the physical configurations of the capacitor namely the total surface area of the conductive capacitor plates and the thickness of the dielectric insulator between the conductive plates of the capacitor. Accordingly, in order to decrease the physical dimensions of the capacitor while remaining the same capacitance, any reduction in the total surface area of the conductive capacitor plates must be associated with the corresponding reduction in the thickness of the dielectric material or the spacing between the conductive capacitor plates.
Traditionally, prior art capacitors were formed by rolling a first and second foil separated by a dielectric material into a cylindrical roll. Some in the prior art have attempted to miniaturize capacitors by incorporating thin film sheet technology and the like. By utilizing thin film sheet technology, the physical thickness of the conductive capacitor plates is reduced, without reducing the surface area thereof. The use of thin film technology aided in the physical reduction of the physical size of the capacitor for a given capacitance.
Accordingly, it is an object of the present invention to provide an apparatus and method of making a capacitor having an extremely high capacitance for physical size which was heretofore unknown by the prior art.
Another object of this invention is to provide an apparatus and method of making a capacitor which is extremely reliable and capable of high temperature operation.
Another object of this invention is to provide an apparatus and method of making a capacitor which utilizes a plurality of coaxial capacitors connected in electrical parallel.
Another object of this invention is to provide an apparatus and method of making a capacitor wherein each of the individual coaxial capacitors may be tested for any defects prior to interconnection thereby eliminating the need for scraping the capacitor due to a single defective one of a plurality of coaxial capacitors.
Another object of this invention is to provide an apparatus and method of making a capacitor by drawing coaxial conductors separated by a dielectric material in a wire drawing process.
Another object of this invention is to provide an apparatus and method of making a capacitor by drawing a multiplicity of individual coaxial capacitors in a wire drawing process.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and application is of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention, the detailed description presenting the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.
The present invention is defined by the appended claims with specific embodiments being shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an improved capacitor, comprising an array of a multiplicity of capacitor elements. Each of said multiplicity of said capacitor elements comprises a first capacitor plate element surrounded by a second capacitor plate element with a dielectric material interposed therebetween. A first capacitor plate connector interconnects each of the first capacitor plate elements of the multiplicity of the capacitor elements to form a first capacitor plate. A second capacitor plate connector interconnects each of the second capacitor plate elements of the multiplicity of the capacitor elements to form a second capacitor plate.
In one embodiment of the invention, the first capacitor plate elements includes a metallic wire having a substantially circular cross-section. The dielectric material may include an oxide on each of the first capacitor plate elements or may include a coating on each of the first capacitor plate elements.
In another embodiment of the invention, each of the second capacitor plate elements includes a metallic tube in the form of a continuous metallic tube about each of the first capacitor plate elements and the dielectric materials. The first capacitor plate connector includes each of the first capacitor plate elements having an exposed portion. The first capacitor plate connector interconnects each of the exposed portions of each of the multiplicity of the first capacitor elements to form the first capacitor plate. The second capacitor plate connector includes the multiplicity of the capacitor elements being disposed within a second metallic tube and being in electrical contact therewith.
The invention Is also incorporated into the process for making a capacitor, comprising the steps providing a first capacitor plate element. The first capacitor plate element is covered with a spacing material selected for forming a capacitor dielectric. The first capacitor plate element and the spacing material are encased with a second capacitor plate element. A multiplicity of the capacitor elements are inserted within a second capacitor plate connector. The second capacitor plate connector is drawn for reducing the outer diameter thereof and for electrically interconnecting the multiplicity of the second capacitor plate elements with the second capacitor plate connector to form a second capacitor plate. The multiplicity of the first capacitor elements are interconnected with a first capacitor plate connector to form a first capacitor plate.
In a more specific embodiment of the invention, the step of covering the first capacitor plate element with the spacing material selected for forming a capacitor dielectric includes chemically replacing the spacing material with a dielectric material. Preferably, the first and second capacitor plate elements with the spacing material therebetween are immersed within an acid for removing the spacing material from between the first and second capacitor plate elements. Thereafter, a dielectric material is formed between each of the first and second capacitor plate elements.
In a more specific embodiment of the invention, the first capacitor plate element is a metallic wire having a substantially circular cross-section. In one embodiment of the invention, the second capacitor element is a first metallic tube such as a preformed first metallic tube or a continuous tube formed about the first capacitor plate element and the spacing material. When the second capacitor plate element is drawn, the first capacitor plate element and the second capacitor plate element are moved into engagement with opposed sides of the spacing material.
Preferably, a multiplicity of the capacitor elements are formed into an array. The array of the capacitor elements are simultaneously encased within the second capacitor plate connector. Preferably, the second capacitor plate connector is a second metallic tube such as a preformed second metallic tube or a continuous tube formed about the array of the capacitor elements.
The step of drawing the second capacitor plate connector electrically interconnects the multiplicity of the second capacitor plate elements with the second capacitor plate connector by diffusion welding the second capacitor plate elements to the second capacitor plate connector to form a substantially unitary material.
The multiplicity of the first capacitor elements are interconnected with a first capacitor plate connector to form a first capacitor plate. Preferably, a portion of each of the first capacitor plate elements of the array of capacitor elements are exposed for connection to the first capacitor plate connector.
A portion of each of the first capacitor plate elements of the array of capacitor elements may be exposed by chemically removing a portion of the second capacitor plate elements and the second capacitor plate connector. The exposed portion of each of the multiplicity of the first capacitor elements are interconnected with the first capacitor plate connector.
In one embodiment of the invention, the second capacitor plate elements and the second capacitor plate connector are immersed into an acid for dissolving a portion of the second capacitor plate elements and the second capacitor plate connector and for exposing a portion of each of the first capacitor plate elements of the array of capacitor elements. The exposed portion of each of the multiplicity of the first capacitor elements are interconnected with the first capacitor plate connector.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It also should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.